Process to improve heat stability of polyoxymethylene



United States Patent 3,337,505 PROCESS TO IMPROVE HEAT STABILITY OF POLYOXYMETHYLENE Muneyoshi Minami, Yoshizo Tsuda, Kiichiro Sando, Junzo Kashiro, and Kiyoshi Tamura, Shiga-ken, Japan, assignors to Toho Rayon Kabushiki Kaisha, Tokyo, Japan, a corporation of Japan N0 Drawing. Filed Oct. 8, 1963, Ser. No. 314,629 11 Claims. (Cl. 260-67) The present invention relates to a process to improve heat-stability of polyoxymethylene employing a compound (which hereinafter is called N-peracylamide) having at least one nitrogen atom to which nitrogen atom at least 2 carboxylic acyl radicals or one carboxylic acyl radical and at least one thiocarbonyl radical are bound.

Macro-molecular polyoxymethylene itself is superior in chemical as well as thermal stability to low molecular polyoxymethylene, however, its Weak point is that the stability is lost as time passes by. As a matter of fact, in order to meet the commercial demand, in carrying out heat-treatment thereof in molding, some additional treatment must be done.

This weak point mentioned above is mainly attributable to the hydroxyl group existing as a terminal group, and attempts have long been advocated so far to enhance the heat-stability by esterificating or etherificating this unstable terminal group, for example, as in Hochmoleculare Organische Verbindungen, Springer-Verlag (1932), by H. Staudinger. There have already been proposed commercial scale processes for esterification of the terminal OH of polyoxymethylene, Where carboxylic anhydride or ketene is used as acylating agent.

We have found that the terminal OH of polyoxymethylene can be very effectively acylated by N-acylamides having in its molecule at least one nitrogen atom to which nitrogen atom at least 2 carboxylic acyliradicals are bound, or one carboxylic acyl radical and at least one thiocarbonyl radical are bound.

In the present invention, as acylating agent N-peracylamide whose general formula shown below can be employed.

R2 R-C OI IXR1 (I) (wherein X represents carbonyl or thiocarbonyl, R represents optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted .aryl or optionally substituted heterocyclic; R represents optionally substituted alkyl, optionally substit-uted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclic, optionally substituted alkenyl, alkoxy, carba'lkoxy, substituted amino or substituted carbamoyl; R represents hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclic, optionally substituted alkenyl, carboxylic acyl or substituted amino; and R and R when taken together, may form a heterocyclic ring with the nitrogen atom and X).

In the Formula I, R may be an alkyl having 1-20 carbon atoms or an aryl such as phenyl or naphthyl. Alternately, R may be a cycloalkyl such as cyclohexyl or cyclopentyl or a heterocyclic group such as furyl, thienyl, pyridyl, pyranyl or benzopyranyl. Furthermore, R can have one or more substituents such as alkyl, aryl, alko-xy,

alkylthio, halo or nitro. Thus, R may be fluoromethyl,

3,337,505 Patented Aug. 22, 1967 may be an alkoxy such as methoxy or ethoxy, a carbalkoxy such as carbomet'hoxy or carbethoxy, a substituted amino such as dimethylamino or piperizinoarnino, or a substituted carbamoyl such as N-phenyl-Nmethyl-carbamoyl, N-phenyl-N acetyl carbamoyl or N diacetylamino-N-acetyl-carbamoyl.

R may be hydrogen, but preferred R is a suitable organic group. The representation of R covers real big range. It can be an alkyl of 1-20 carbon atoms, an alkenyl of 1-20 carbon atoms, a cycloalkyl of 5 or 6 ring carbon atoms, an aryl such as phenyl, napthyl or anthryl, a heterocyclic groupl such as furyl, thienyl, pyridyl, pyranyl, quinolyl, benzpyranyl, quinazolinyl, oxazolyl, thiazolyl, morpholino, piperidino, succinimido, phthalirnido, pyrrolyl, imidazolyl, piperazino,triazolyl, tetrazolyl, or their hydroor oxo-derivatiVes.

In case R is a heterocyclic group having NH, it is preferred that yl is on that position, or the hydrogen atom is replaced with a suitable substitutional radical. R can have one or more substituents such as alkyl, aryl, cycloalkyl, heterocyclic, alkoxy, aryloxy, alkylthio, halo, nitro, cyano, acyl, acyloxy, carbalkoxy, substituted amino, substituted carbamoyl or substituted sulfamoyl. Thus, R may be tolyl, xylyl, dodecylphenyl, ethylcyclohexyl, benzyl, phenethyl, cyclopentamethyl, furfuryl, ethoxymethyl, methoxyphenyl, ethoxyphenyl, phenoxyphenyl, ethylthioethyl, fluoromethyl, chlorophenyl, nitrophenyl, cyanophenyl, acetylphenyl, 9-acetyl-carbazolyl, 4-acetyl- 2,6-dioXo-piperazine-l-yl, acetoxyethyl, B-diacetylaminoethyl or dimethylsulfamoylphenyl, Z-phenylquinazolone- 3-yl, or 3,5-diphenyl-4H-1,2,4-triazole-4-yl. Furthermore, R may be a carboxylic acyl such as acetyl or benzoyl, or a substituted amino such as dimethylamino, diphenylamino, acetylamino, N-methyl-N-acetylamino, diacetylamino, N-acetyl-N-benzoyl-amino or N-acetyl N (1H- 1,2,3,4-tetrazole-1-yl) amino.

In the Formula I, R and R when taken together, may form a heterocyclic ring With N and X. For example, they may form a lactam ring such as caprolactam, phthalimidine or oxoindole, a dicarbimide ring such as succinimide, adipi mide, phthalimide or naphthalimide, a dicarbohydrazide ring such as succinhydrazide or phthalhydrazide, or other heterocyclic ring such as 2,3- or 2,6- dioxo-piperazine, 2,6-dioXo-morpholine, 2,6 dioxo thiomorpholine, oxazolidone, hydantoin, thiohydantoin, imidazolone, isatin or acetylenediurein.

The following are some of the examples of N-peracylamides which can be employed to the process of this invention.

diacetamide dipropionarnide distearamide dibenzamide difuramide N methyldiacetamide N-butyl-diacetamide N-launyl-diacetamide N-heptadecyl-diacetamide N-fl-pyridyl-diacetamide N-methyl-distearamide N-ethyl-idifiuoroacetamide N-cetyl-diethoxyacetamide N-butyl-difl-ethylthiopropionarnide N-diacetylaminoethyl-diacetamide N-butyl-difurarnide N-acetoxyethyl-diacetarnide N-allyl-diacetamide N-acetylnylon N-cyclohexyl-diacetamide 3 N-cyclopentyl-methyl-diace-tamide N-ethylcyclohexyl-diacetamide N-methyl-dicyclohexyl carboxylic amide N-butyl-dibenzamide N-ethyl-dinaphthamide N-butyl-dimethoxybenzamide N-butyl-ditoluamide N-methyl-dichlorobenzamide N-ethyl-dichloronitrobenzamide diacetanilide :dichloroacetanilide dipalmitanilide di-a-chloropropionanilide di-a-ethylthiopropionanilide diacetotoluidide diacetododecylanilide diacetoxylidide diacetanisidide diacetophenetidide diacetophenoxyanilide diacetocyanoanilide diacetoacetylanilide diacetodimethylsulfamoylanilide diacetoni-troanilide diacetochloroanilide 'diacetodichloroanilide diacetonaphthylamide diacetanthrylamide diacetobenzylamide 6-quinolyl-diacetamide N-acethylcarbazolyl-diacetamide 3 -diacetylamino-Z-phenylquinazolone 4-diacetylamino-3 ,S-diphenyl-1,2,4-triazole 4-diacetylami'no-3 ,4-dihydrocumarin N-acetyl-benza-mide zdibenzanilide dichlorobenzanilide N-acetyl-benzanilide N-acetyl-furanilide N-methyl-N-chloroacetyl-naphthamide N-crotonoyl-benzanilide N-methyl-N-cinnamoyl-acetamide triacetamide tribenzamide N-acetyl-dibenzamide N-acetyl-caprolactam. N-acetyl-phthalimidine N-acetyl-oxoindole N,N'-diacetyl-2,S-dioxopiperazine N-acetyl-succinimide N-acetyl-adipimide N-acetyl-phthalimide N-acetyl-naphthalimide N-benZoyl-succinimide N-benzoyl-phthalimide N-acetyl-4-phenyl-2,6-dioxomorpholine N-acetyl-4-phenyl-2,6-dioxopiperazine N-acetyl-Z,6-dioxomorpholine N-acetyl-2,6-dioxothiomorpholine N-acetylurethane N-methyl-N-acetylurethane N-dimethylcarbamoyl-acetamide N-piperidinocarbamoyl-acetamide N-carbethoxy-acetanilide 3-acetyl-2-oxazolidone 1,3-diacetylhydantoin 1,3-diacetyl-4-diacetylaminomethylimidazolone tetra'cetylacetylenediurein oxalyl-bis-(-N-acetanilide) N,N-dibenzoyl-N,N'-dimethyloxamide N-methyl-N-ethoxalyl-acetamide N-acetyl-isatin N,N-diacetyl-2,3-dioxopiperazine 4 N,N-dimethyl-N,N-diacetylhydrazine N,N-diphenyl-N',N'-diacetylhydrazine triacetylhydrazine triacethylmethylhydrazine tetraacetylhydrazine N,N-dibenzoyl-N,N'-diacetylhydrazine hexaacetyl-oxalhydrazide S-triacetylhydrazinotetrazole N-morpholino-diacetamide N-diacetylamino-succinimide N,N-diacetylsuccinhydrazide N-acetyl-N'-phenylphthalhydrazide N-acetyl-N'-methylphthalhydrazide N,N-diacetylphthalhydrazide N-acetyl-thioacetanilide N-acetyl-ethylthiocarbamine 3-acetyl-2-thiohydantoin N-acetyl-thiobenzanilide In the present invention, polyoxymethylene is a homopolymer of formaldehyde or trioxane, or a copolymer obtained by copolymerizing trioxane with a suitable copoly-merizable monomer such as dioxolane, dioxepane, or styrene.

According to the process of this invention, it is not always necessary to have a catalyst to acylate the terminal radicals of polyoxymethylene. However, ordinarily it is desirable to employ an acylating catalyst. As acylating catalysts, hitherto known acylating catalysts can be employed in acyl exchange in so far as, they do not decompose polyoxymethylene to a remarkable extent, however, according to the process of this invention, the basic salts of alkaline metals, the basic salts of alkaline earth metals, organic bases, the salts made from organic bases and acids, and the acylating catalysts selected from among the groups made up from Lewis acid and Lewis acid complex compounds are preferable.

As such acylating catalysts, the basic salts of alkaline metals, such as sodium acetate, potassium acetate, and the basic salts of alkaline earth metals such as calcium acetate, and organic bases such as dimethylaniline, diethylaniline, pyridine, pycoline, lutidine, quinoline, triethylamine, tripropylamine, tributylamine, tetra alkyl ethylenediamine, alkylmorpholine, alkylpiperidine, alkylpiperazine, etc., can be employed.

In addition, their salts of fiuoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, and their quaternary ammonium salts such as fluoride, chloride, bromide or iodide with the radical such as methyl, ethyl, propyl, butyl, octyl, cetyl, benzyl, or phenethyl, can be employed. As to organic bases, they are especially preferably acylating catalysts and the greater the basicity is, the better becomes the catalysing efliciency.

The amount of acylating catalyst employed against polyoxymethylene can be varied in wide range, but on average, in case of organic bases, 1 to 50% by weight, or more preferably 3 to 30% by weight, and in case of other salts and complex compounds, 0.0001 to 1% by weight or more preferably 0.001 to 0.1% by weight can be applied there to.

Substitutional acylating reaction is carried out usually at room temperature up to 250 C., or more preferably between to C.

Here, there is no special restriction on the employed amount of N-peracylamide against polyoxymethylene, however, 2 to 10 times by weight can be preferably employed.

The reaction can be carried out without employing the solvent, however, even employing the solvent, the reaction can be carried out likewise. As the example of such a solvent as mentioned above, y-butyrolactone, acetophenone, dimethyl formamide.

In case the solvent is employed the amount employed may be sufiiciently 10 to 100% by weight against N-peracylamide.

In the acylating reaction by means of N-peracylamide as proposed by this invention, it is possible to control the decomposition of polyoxymethylene in the process of the reaction, and to obtain the aimed product in a more pref- (5) In the process of this invention, the acidamides or acidimides produced as the result of the reaction are changed into N-peracylamide by the reacylation thereof with ac-idanhydride, for example, and again can be emerable state by adding one or more cracking controllers 5 ployed to the process of this invention.

such as carbodiimides, isocyanates, isothiocyanates, cyan- The following are the examples to further illustrate the amides, epoxy compounds, vinylesters, or thiovinylethers. present invention.

Such cracking-controllers can be applied by the amount of As macro molecular polyoxymethylene, the following 0.2 to 20% by weight against polyoxymethylene. are employed;

The employment of hitherto known terminal treatment 10 (l) Polymer (POM-l) obtained by irradiating 1 mr. agent along with the N-peracylamide of the present invenof electron-ray onto crystal trioxane which is subjected to tion will not spoil the effect thereof. heat-polymerization at 55 C., for 2 hours, and is rinsed By the addition of amide stabilizer such as nylon, or carefully with acetone so that no trioxane is left over, and bisphenol antioxidant, the better heat stability of macro is vacuum-dried. polyoxymethylene is obtained, (2) Polymer (POM-2) Obtained by well mixing crys- In carrying out the acetylation of polyoxymethylene the tal trioxane with 0.03% triethyloxonium borofluoric acid process of this invention is better in the following points salt as a catalyst dissolved in 1% methylene chloride soluthan hithertofor practiced process employing carboxylic tion, which mixture is subjected to heat-polymerization acid anhydride. at 58 C. for 2 hours, and is filtered, rinsed with acetone,

(1) Ordinary anhydrous carboxylic anhydride always and then vacuum-dried. produces free carboxylic acid, and this carboxylic acid (3) Polymer (POM-3) obtained by having 5% butylreacts upon polyoxymethylene causing cracking thereof, vinyl co-axisted with 80% trioxane, n-heptane solution, lessening the yield of polymer, reducing the degree of and by subjecting this to reaction at 70 C. along with polymerization, and worsening the heat stability of the 0.02% triethyl oxonium borofluoric acid salt as a catalyst. polymer obtained, (4) Copolymer (POM-4) obtained by subjecting to re- While the N-peracylamides of this invention produce act on along with 15% styrene. in the reaction only acidamides, or acidimides, which do (5) Copolymer (POM-5) obtained by adding 5% not merely cause the decomposition of polyoxymethylene, formal dioxepane to 80% trioxane heptane solution, and but rather promote heat stabilization of polyoxymethylthen by copolymerizing this mixture with 0.02% triethylene synergistically. oxonium boric-fluoric acid salt.

(2) In carrying out the acylation of polyoxymethylene, (6) Polymer (POM-6) obtained by polymerizing forit is more preferable to carry out the reaction in melting maldehyde anhydrous gas through jetting into heptane state homogeneously than heterogenously. at 0 C. along with 0.01% tributyl amine, and then by In case of the polymer obtained by polymerizing trifiltering, rinsing with acetone, and finally by vacuum dryoxane in solid phase, especially the above is hoped for, ingbecause the degree of the crystalization ih higher than the The degree of POIYmeTiZatiOH f these p ymer s polymer obtained from the solution of trioxane or formalrepresented y 711 11 Which is Obtained by measuring respecdehyde as, tive viscosity of 0.5% parachlorphenol solution at 60 C.

In order to carry out the reaction homogeneously the containing 2% u-pinene. employment of the compound having the boiling point of 40 The Percentage of decreased amount of P y as it is 180 C. or more is preferable because polyoxymethylene heaved :at 200 C. for 30 minutes or 60 minutes is dewhose melting point is about 180 C., becomes easily scribed y D or D as a means of describing heatsoluble in solvent around the temperature. On this point, Stabilityas given before N-peracylamides are all of high boiling The percentage of decreased amount of P y when point, and especially against polyoxymethylene, these are 1% methylene bis-4-methyl-6-tertiary-butylphenol as antigood solvents, and they are convenient for carrying out oxidant, and copolymer comprising 3% nylon 6 and nylon the reaction homogeneously so that it is not necessary to 610 as a polyamide heat stabilizer are added thereto, is add the third good solvent. represented by D NA.

(3) In case N-peracylamides of high boiling point are employed, the reaction can be carried out under atmos- Example 1 pheric pressure, and in such acase the recovery of formal- 3 grams of ground trioxane polymer is heamreated at ciehyde'gas Whlch partly produced through the decomposl' 165 C. for an hour along with 30 grams of 'y-butylolactron of polyoxymethylene becomes easy. t l d f 1 (4) In case acylation is 'done by carboxylic acid anone so u Ion W or W out Vanous i 0 cata ysts' hydride, formaldehyde produced by the decomposition of After reaction the Freated matter is f filt ered a part of polymer in the reaction, is easy to react upon nnsedf and thus wh 1te W 1s obtamed' carboxylic acid anhydride to produce methylene dicar- Theylelflimg heat crackmg and the degree boxylate, and causes a loss of the reagent for reaction. of Vlscoslty areglven Table I below However, above mentioned N-peracylamides of high AS in Observed in the table, 200 of untreated P y boiling point mostly do not react on formaldehyde, and is 570%, zoo being and heat'stability is the loss during reaction is substantially very little. very much ameliorated.

TABLE I Cone. of Amount Reactant, Catalyst to be Yield D2003, D1007) NA un percent ad e percent percent 30 Sodium Acetate 0.01 45.3 15 2.2 1.70

30 Pyridine 1.0- 5.4 0.9

10 None 51.5 18.0 2.4 1.76

7 Example 2 A result obtained when N-acetyl phthalimide is employed as a reaction reagent in the above reaction, is given in Table II.

' As to the degree of polymerization, of acetylated polymer is 1.34 against 1.40 of the untreated polymer and thus no remarkable change is observed.

1 Reaction Tin1e= a half hour.

The heat-stability is very much improved as described -by the table.

Example 3 30 grams of POM-2 is mixed with 90 grams of diacetanilide and the mixture is put into a flask and the air within the solution and inside the flask is completely replaced for nitrogen-gas at 70 C.80 C., and then the mixture is subjected to reaction at 175 C. for 1.5 hours.

After the reaction 90 grams of -butylolactone preheated at 175 C. is added at once.

The solution is cooled off, filtered, rinsed with acetone, and vacuum dried.

Thus, white acetylated polymer is obtained.

The yielding ratio is 94%; D is 21.8%; D NA is 0.5%.

While untreated polymer has D being 38%, and D NA being 12.1% and in comparison with the above, the heat stability is very much improved.

In regard to the degree of polymerization of this polymer before and after the reaction, m of acetylated polymer is -1.38 against 1.40 of untreated polymer, and no remarkable change is observed.

Example 4 The mixture of 10 grams of POM-2 and 100 grams of diacetanilide is mixed with 10% antioxidant, diphenylamine, and the mixture is subjected to reaction at 170 C. for 1.5 hours.

The solidified polymer after cooling is ground, and carefully rinsed with acetone, and filtered, and vacuumdried.

The obtained white polymer has the yielding ratio of 95%, B20060 being DZQOSONA being In this case too, heat-stability is remarkably enhanced.

Example 5 In case 0.1% dibenzyldisulfide in place of diphenylamine is added in the above case, the yielding ratio of polymer is 94%, D being 24.3%, D being 0.6%.

Example 6 The mixture of grams of POM-2 and 100 grams of diacetanilide is subjected to reaction in the presence of 0.01% cetylpyridinumchloride.

The rinsing, in this case, of acetylated polymer is carried out with warm alcohol for 3 or 4 times, and specially carefully it is rinsed.

The yielding ratio is 98%; D is 27.2%; D NA is 0.7%.

Example 7 In place of the cetyl pyridinumchloride as a catalyst in the foregoing case, 10% pyridine is added to the reaction mixture, and the yield in this case is 90; D is 0.9%

Example 8 In the foregoing Example 3, formaldehyde polymer (POM-6) is employed, and the reaction is carried at 160 C. for 2 hours and yield is 88% D is 0.8%; m is 1.5.

The untreated polymer has D being 38.4%, and m being 1.5.

Example 9 Example 10 In the foregoing Example 9, the solution of 10 grams of acetylphthalimide and 40 grams of y-butyrolactone as solvent are subjected to reaction.

The polymer coming out as cooling treatment is carried out is subjected to the same treatments as in the foregoing cases.

Thus obtained polymer has the yield of 83%, D being 0.7%, and 1 being 1.45.

Example 11 In the foregoing Example 9, the solution of 25 grams of acetylphthalimide, and 25 grams of -butyrolactone solution are subjected to reaction in the presence of 0.1% sodium alcoholate.

The obtained polymer has the yield of 90%, D being 21.8%, D being 0.8, and m being 1.43.

Example 12 0.1% antioxidant diphenylamine is added to the mixture of 10 grams of POM-3, 25 grams acetylphthalirnide and 25 grams of solvent anisole, and this is subjected to reaction at 180 C. for 30 minutes.

Thus obtained polymer has the yield of 96%, D being 0.3% and 1 being 1.24.

The untreated polymer has D being 11.6% and 1 being 1.31.

Example 13 10 grams of POM-4, 30 grams of acetylphthalimide, 30 grams of solvent acetophenone are subjected to reaction at C. for 1.5 hours.

The obtained polymer has the yield of 98%, D being 0.5%, and m being 1.34.

The untreated polymer has D being 13.5% and Example: N-peracylamide 111mb being 1.37. Diacetamide.

Example 14 16 N-methyl-diacetamide.

The mixture of 10 grams of POM-5 and 30 grams of 17 N'heptadecyl'diacetamlde' diacet lid b'e ted to eaction at 170 C for 15 5 18 N'cyclohexyl'dlacetamlde' ifi g 511 1 c T 19 Diacet-o-toluidide.

After reaction, this is poured in a fine stream into 20 21 D1acet-p-phenet1d1de. acetone whlle Well st1rr1ng, and the sol1d1fied polymer d d d aceton nd vacuum 22 D1acet-m-n1troan1l1de. a g an again nnse W1 a 10 23 Dichloroacet-anilide.

Thus White acetylated polymer is obtained. glgfiethylthlopropmnamhde ONA 1 enzamhde. The y1eld thereof 18 95%, D thereof belng 0.6%, 26 D M GONA -m-c orobenzanlhde. wh1le the untreated polymer has D belng 10.8%,

27 N-benzyld1acet-am1de. and heat-stab1l1ty 1s very much enhanced. 28 N 15 -acetylbenzan1l1de. As to the degree of polymerlzatlon of acetylated 29 N furfuryld1acetarn1de. polymer 1s 1.31 agalnst 1.35 of the untreated polymer b 30 N butyld1fu1'am1de. and no remarkable change was 0 Served 31 4-diacetylarnino-3,4-dihydrocumarin.

Examples ]5 52 32 N-fi-pyridyldiacetamide.

20 33 4-diacetylamino-3,S-diphenyl-l,2,4-triazo1.

3 grams of the polymer obtained by polymerizlng tr1- 34 N-acetylcaprolact-am. oxane with the catalyst in solid phase such as POM-2 is 35 N-acetylphthalimidine. subjected to reaction at,a given temperature for a given 36 NN-diacetyl-2,S-diketopiperazine. period of time against 500% weight of the reagent or 37 N-acetylsuccinimide. its solution of a suitable solvent of a given concentration. 25 38 N-acetyl-Z,6-diketomorpholine.

After reaction the treated matter is poured into acetone, 39 N-acetyl-4-phenyl-2,6-diketopiperazine. and thus obtained polymer is treated by Soxhlet apparatus 40 N-acetylurethan. along with acetone or methanol continuously, and the 41 NN'-diacetylhydantoin. excessive reagent is removed as much as possible, and 42 N-tetra-acetylacetylenediurein. then vacuum dried, and the result is shown on Table 3. 30 43 N-methyl-N-ethoxacylacetamide.

The heat-stability thereof is much improved when com- 44 Oxalyl-bistN-acetanilide). pared With untreated polymer With D being 27.3%, 45 NN-diacetyl-2,3-diketopiperazine. 601111 being 3.3% 46 N-acetylisatin.

In regard to the degree of polymerization of thus ob- 35 47 N-diacetyl-N-dimethylhydrazine. tained polymer in this reaction m being 1.38 is not 48 Tetraacetylhydrazine. almost affected, and as a matter of fact, the toughness 49 N-diacetylamino-succinimide. thereof is the same in forming film by adding A14, nylon 50 NN'-diacetylphthalhydrazide. thereto. 51 N-acetyl-thiobenzanilide.

N-peracylamide employed: 40 52 N-acetylthiohydantoin.

RESULTS Exs. Cone. Solvent Temp. Time Yield B26030 DQODKUNA "in No. (percent) 0.) (hrs) (percent) (percent) (percent) 70 BL 165 1 61 13.8 1.7 70 BL 170 1 65 15.2 1.9 BL 165 1 58 16.2 2.1 70 AP 170 1 54 16.7 1.1 100 170 1. 5 92 10. 6 0. 5 100 170 1. 5 94 13. 9 0. 4 100 170 1. 5 12. 4 0. 3 70 A 170 1. 5 87 14. 3 0. 5 70 A 165 1.5 73 15.2 0.7 70 A 170 1.5 88 9.8 0.5 70 A 170 1.5 91 11.4 0.8 70 AP 170 1. 5 87 13.1 0. 9 175 1 86 12.7 0. 4 70 A 170 1.5 89 11.8 0.4 100 1 86 10.8 0. 5 70 A 1.5 83 13.5 0.9 60 A 170 1. 5 78 10. 6 0. 9 70 A 170 1 74 9.1 0.6 70 A 170 1 68 16.2 1.1 100 170 1 73 13.1 0.8 70 BL 170 1 71 14.1 0.6 70 BL 170 1 66 10.2 0.8 80 A 170 1 89 10.8 0.3 80 A 170 1 95 12.5 0.4 70 A 165 1. 5 93 11. 5 0. 5 70 BL 170 1 73 12.8 1.0 70 BL 170 1 70 13.3 1.1 70 BL 170 1 72 11.7 0.9 80 A 165 1 74 13.7 1.3 80 A 165 1.5 72 12.7 1.0 70 BL 165 1. 5 78 13. 9 1. 0 70 A 170 1 86 11.9 0.8 80 A 170 1. 5 89 10.2 0. 9 80 BL 170 1 92 12.8 0.6 70 BL 170 1. 5 90 10. 7 0. 5 70 BL 165 1. 5 87 11.6 0. 9 80 A 170 1. 5 78 12.1 0. 8 80 A 170 1. 5 69 14. 7 1.1

wherein X represents carbonyl or thiocarbonyl, R represents an alkyl having 1 to 20 carbon atoms, a cycloalkyl, an alkenyl of 1 to 20 carbon atoms, an aryl compound selected from phenyl, naphthyl, an oxygen or nitrogen containing heterocyclic group; R represents an alkyl having 1 to 20 carbon atoms, a cycloalkyl, an alkenyl having 1 to 20 carbon atoms, an aryl compound selected from phenyl, naphthyl an anthryl, a lower alkoxy, a lower alkoxy carbonyl, a substituted carbamoyl, a substituted amino or an oxygen or nitrogen containing heterocyclic group; R represents a hydrogen atom, an alkyl having 1 to 20 atoms, a cycloalkyl, an aryl compound selected from phenyl, naphthyl, or anthryl, an alkenyl having 1 to 20 carbon atoms, a substituted amino, or an oxygen or nitrogen containing heterocyclic group, and R and R when taken together, form a heterocyclic ring with a nitrogen atom and X.

2. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane comprising the steps of reacting the hydroxyl terminal groups of said compounds with N- acetyl phthalimide as an acylating agent at a temperature in the range of from room temperature to 250 C.

3. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal groups of said compounds with diacetanilide as an acylating agent at a temperature in the range of from room temperature to 250 C.

4, A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal groups of said compounds with N-methyl-diacetamide as an acylating agent at a temperature in the range of from room temperature to 250 C.

5. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal groups of said compounds with N-ethyl-diacetamide as an acylating agent at a temperature in the range of from room temperature to 250 C.

6. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal groups of said compounds with N-acetoxy-ethyl-diacetamide as an acylating agent at a temperature in the range of from room temperature to 250 C.

7. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal groups of said compounds with N-allyl-diacetamide as an acylating agent at a tem perature in the range of from room temperature to 250 C.

8. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal grou-ps of said compounds with diacetotoluidide as an acylating agent at a temperature in the range of from room temperature to 250 C.

9. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal groups of said compounds with diacetanisidide as an acylating agent at a temperature in the range of from room temperature to 250 C.

10. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal groups of said compounds with diacetophenetidide as an acylating agent at a temperature in the range of from room temperature to 250 C.

11. A process for the stabilization of homopolymers of formaldehyde or trioxane and copolymers of trioxane with a copolymerizable monomer selected from styrene, dioxolane and dioxepane which comprises the steps of reacting the hydroxyl terminal groups of said compounds with N-acetyl-succinimide as an acylating agent at a temperature in the range of from room temperature to 250 C.

References Cited UNITED STATES PATENTS 2,844,561 7/1958 Bechtold et a1 260-67 2,964,500 12/1960 Jenkins et al. 260-67 3,017,389 1/1962 Langsdorf et al. 260-67 3,046,251 7/ 1962 Wagner 260-67 3,116,267 12/1963 Dolce 260-459 3,131,165 4/1964 Hermann et al 260-459 3,155,636 11/1964 Kritzler et al. 260-67 3,274,149 9/1966 Berardinelli 260-458 WILLIAM H. SHORT, Primary Examiner.

L. M. PHYNES, Assistant Examiner. 

1. A PROCESS FOR THE STABILIZATION OF HOMOPPLYMERS OF FORMALDEHYDE OR TRIOXANE AND COPOLYMERS OF TRIOXANE WITH A COPOLYMERIZABLE MONOMER SELECTED FROM STYRENE, DIOXOLANE AND DIOXEPANE COMPRISING THE STEPS OF REACTING THE HYDROXYL TERMINAL GROUPS OF SAID COMPOUNDS WITH ACYLATING AGENTS AT TEMPERATURES RANGING FROM ROOM TEMPERATURE 250*C., SAID ACYLATING AGENT COMPOUNDS HAVING THE GENERAL FORMULA 